Unbiased information or advice is fair, because the person giving it is not being pulled to one side — not by their own opinions, not by their own interests, not by what other people want them to say. To understand it you need 'bias' first: a bias is a lean, a tilt, a pull towards one side that you may not even notice in yourself. So unbiased means standing straight, judging what is actually there. The words it goes with are worth memorising as a set: unbiased advice, unbiased information, an unbiased opinion, an unbiased report, an unbiased view, and for people, an unbiased judge or observer. Two things learners often miss. First, unbiased is about fairness of judgement, not about knowing a lot — an unbiased person can still be wrong, they are just not tilted. Second, the strongest use of the word is about having nothing to gain. If a shop assistant tells you which phone is best, they may be perfectly honest, but they are not unbiased; they get paid either way only if you buy. That is why you so often see 'free, unbiased advice' from consumer groups and charities: the selling point is precisely that nobody profits from the answer. The spelling has two accepted forms, unbiased and unbiassed. Unbiased with one s is far commoner; use that. Its close relative is 'impartial', which is a touch more formal and used more about people and decisions; 'objective' is another neighbour, but that one leans towards 'based on facts, not feelings'. The opposite is 'biased'.